None of the current crown princesses are classically pretty women in the mold of a Princess Grace or a Queen Paola (in their respective youths). So, in the absense of great beauty, thinnness, skin, hair, style, money, grooming and luck determine looks. Here is my rundown:
Letizia: The most interesting to look at. Certainly not classically pretty, but she has a delicacy (in part due to her thinness, I think) that is very compelling. She also has, despite her thinness, curves in the right places. There is something likeable about her face and expression, and she grows on me more with time.
Mary: Also interesting to look at, but in a less positive way. I'm not a big fan, but I think she has great legs and occasionally I like her clothes. Her face is odd; I find myself trying to figure out what is wrong there, although sometimes the camera catches her at the right angle and she looks really good. Her biggest flaw is her expression; even when she smiles she doesn't look truly happy. I can't figure it out.
Mathilde: She radiates serenity. She is lovely and I enjoy her pictures. But she is not as purely interesting to look at as some of the others.
Mette: I kind of admire her determination, but not her looks. She is very straight and flat; her hair is straight, she is tall and her clothes are tailored. Even the hair piece she wore recently instead of a hat was a flat bow on a band. She looks best when pregnant, probably because of the roundness. In general, I find her looks and choice of clothes kind of boring.
Maxima: She is all about the smile. How can you not like her? I don't think she is aging well (too much sun?) but she will just smile more and wear brighter colors and bigger hats. Good for her.
Camilla: There is something to be said for being truly happy. She may not be beautiful or even a little pretty, but she has self respect, a surprisingly good sense of style and a man that really, really loves her. So she glows.
What is great about each of these women is that they were chosen despite their average looks to be the wives of some of the most eligible bachelors of our time. So there's hope for all of us.